Marked eosinophilia in interleukin-5 transgenic mice fails to prevent Trichinella spiralis infection.

In order to study the role of eosinophils in the host defense against Trichinella spiralis infection, worm recovery after infection with T. spiralis was compared between interleukin-5 transgenic (IL-5 Tg) mice with a constant high level of peripheral eosinophils and nontransgenic C3H/HeN mice. No significant difference in the recovery of muscle larvae or adult worms in the small intestine, fecundity of female adult worms, or infectivity of newborn larvae was observed between nonimmunized C3H/HeN and IL-5 Tg mice or C3H/HeN and IL-5 Tg mice immunized with somatic antigen of T. spiralis. However, a significant difference was observed in the fecundity of female adult worms and recovery of muscle larvae between nonimmunized and immunized IL-5 Tg mice or C3H/HeN mice. These results demonstrate that having more eosinophils does not improve immunity against the various aspects of T. spiralis infection.